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Warning device for vehicles against an approaching objects

  • US 4,825,211 A
  • Filed: 10/14/1987
  • Issued: 04/25/1989
  • Est. Priority Date: 04/28/1987
  • Status: Expired due to Fees
First Claim
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1. A warning device for use on a vehicle for sensing an approaching object when the vehicle is moving backward, the device producing a first signal when the object is in remote proximity to the vehicle and at least a second signal when the object is in close proximity to the vehicle, the device having a first transistor for receiving on a base thereof an oscillating voltage, a pair of first and second unstable multivibrators said first multivibrator having an output terminal connected to a reset terminal of said second multivibrator, an output terminal of said second multivibrator connected to said base of said first transistor thereby supplying said oscillating voltage, at least one infrared light-emitting diode connected in series with a collector emitter path of said first transistor, said oscillating voltage on said base of said first transistor causing said first transistor to switch on and off thereby providing an intermittent current flowing in said infrared light-emitting diode to produce an intermittent infrared light therefrom, a series circuit having at least one infrared light receiving diode connected to a first inverting amplifier which in turn is connected to a second non-inverting amplifier, which in turn is connected to a band-pass filter, which in turn is connected to a rectifier, and which in turn is connected to a third inverting amplifier, said receiving diode receiving said infrared light reflected by the object from said infrared light-emitting diode, when the object approaches the vehicle, a second transistor having a base connected to an output of said third inverting amplifier, a first AND gate having a first input connected to said output terminal of said first multivibrator and a second input connected to a collector emitter path of said second transistor via a third transistor, said second input of said first AND gate connected to said collector emitter path of said third transistor and a base of said thrid transistor connected to a collector emitter path of said second transistor, comprising:

  • an output of said first AND gate connected to noninverting inputs of both first and second differential amplifiers, inverting inputs of said first and second differential amplifiers being connected via first and second variable resistors, respectively, to an applied voltage;

    first and second outputs of said first and second differential amplifiers, respectively, connected to first and second inputs of a second AND gate;

    an output of said second AND gate connected to a means for producing the second signal and said output of said first differential amplifier connected to a means for producing the first signal.

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